The present invention relates generally to transmissions having counter-rotating output shafts, and, more specifically, to a gas turbine engine having a transmission effective for obtaining equal and opposite speeds of dual output shafts for driving counter-rotating propellers.
Dual output, counter-rotating transmissions for gas turbine engines are known. Such transmissions typically include epicyclic gearsets which are effective for providing counter-rotating output shafts and dividing torque and power received from a gas turbine engine output shaft. However, such transmissions tend to be of the differential type wherein equal and opposite output shaft speed is not maintainable with equal power division without the use of additional, complex synchronizing means and/or a predetermined apportionment of loading torque for maintaining such equal speeds. Furthermore, power requirements for modern gas turbine engines vary from about 8,000 to 11,000 shaft horsepower which, accordingly, requires a suitable transmission effective for handling such relatively high power.
It is desirable to provide transmissions which divide input power substantially equally between two counter-rotating propellers. The transmission should also be light, relatively simple, highly durable, and highly reliable and should have coaxial positioning of input and output shafts, or so-called in-line construction.
It is therefore an object of the present invention to provide a new and improved transmission having counter-rotating output shafts.
Another object of the present invention is to provide a new and improved transmission for a gas turbine engine which is relatively simple yet effective for transmitting power in the range of up to about 8,000 to 11,000 shaft horsepower.
Another object of the present invention is to provide a new and improved transmission effective for obtaining equal and opposite rotation of dual output shafts thereof throughout the transmission's entire speed range.
Another object of the present invention is to provide a new and improved transmission effective for maintaining a fixed, phased relationship between dual output shafts thereof.
Another object of the present invention is to provide a new and improved transmission effective for providing equal torque to dual output shafts thereof while maintaining equal and opposite rotation thereof.